Valerian: Benefits, Dosage, and Safety

What valerian is

Valerian is an herb sold as a dietary supplement in the United States. It comes from Valeriana officinalis, a perennial plant of the Valerianaceae family native to Europe and Asia and naturalized in North America, and is a common ingredient in products promoted as mild sedatives and sleep aids for nervous tension and insomnia. Supplement preparations are made from the plant's roots, rhizomes (underground stems), and stolons (horizontal stems). There is no scientific agreement on which constituents are active; proposed candidates include the volatile oil components such as valerenic acid and its derivatives, and the iridoids known as valepotriates, but its activity may result from interactions among multiple constituents rather than any single compound.

What it does

• Marketed as a mild sedative and sleep aid for nervous tension and insomnia, though ODS states clinical evidence of efficacy for sleep disorders is inconclusive
• Constituents have shown sedative effects in animal and in vitro studies, but there is no scientific agreement on valerian's mechanism of action in humans
• One proposed mechanism is increasing the amount of the inhibitory neurotransmitter GABA available in the synaptic cleft, though whether this contributes to sedation in humans is not known
• Historically used for nervousness, sleeplessness, gastrointestinal spasms and distress, though scientific evidence is not sufficient to support these uses

Intake and dosing

Valerian is not an essential nutrient, so no Recommended Dietary Allowance or Tolerable Upper Intake Level has been set. Doses in studies vary widely. Because supplement doses are not standardised, discuss an appropriate amount with a clinician or pharmacist.

Deficiency and who is at risk

Not applicable. Valerian is an herbal supplement, not an essential nutrient, so there is no Dietary Reference Intake, no requirement, and no deficiency state. It is not needed for normal human physiology.

Who may need more

• No one requires valerian; it is not an essential nutrient and has no established role in normal physiology
• Adults who use it do so as a self-selected sleep aid or mild sedative, but ODS notes the sleep-promoting evidence is inconclusive

Food sources

Not a dietary nutrient. Valerian is obtained only from the root, rhizome, and stolon of the Valeriana officinalis plant, typically consumed as a supplement, tea, or tincture rather than as part of the normal diet.

Forms and absorption

Preparations are made from dried roots, rhizomes, and stolons. Dried roots are prepared as teas or tinctures, and dried plant materials and extracts are put into capsules or tablets. Extracts are sometimes standardized to volatile oils (valerenic acids), sesquiterpenes, or valepotriates, but there is no scientific agreement on the active constituents. Doses used in clinical sleep studies ranged from 400 mg to 900 mg of extract, with 600 mg of a standardized commercial dried-root extract (LI 156) common in the better-rated trials. Constituent levels vary significantly with harvest timing, and because supplements are not always tested for manufacturing consistency, composition may vary considerably between manufacturing lots.

Safety, excess and interactions

Too much

Few adverse events attributable to valerian have been reported in clinical study participants, and long-term safety data are not available. The most common effects reported in clinical trials are headaches, dizziness, pruritus (itching), and gastrointestinal disturbances, though similar effects were also reported with placebo. In one study, increased sleepiness was noted the morning after a 900 mg dose. Several case reports have described adverse effects; in one reported suicide attempt with a massive overdose, the symptoms could not be clearly attributed to valerian. Valepotriates, a component that is not necessarily present in commercial preparations, showed cytotoxic activity in vitro but were not carcinogenic in animal studies.

Interactions to know

• Benzodiazepines such as alprazolam (Xanax), diazepam (Valium), lorazepam (Ativan), and triazolam (Halcion) - possible additive sedative effects
• Barbiturates and central nervous system (CNS) depressants such as phenobarbital (Luminal), morphine, and propofol (Diprivan) - possible additive sedative effects
• Alcohol and other sedative drugs - theoretical possibility of additive sedative effects
• Dietary supplements with sedative properties such as St. John's wort, kava, and melatonin - possible additive therapeutic and adverse effects
• Valerian has not been reported to influence laboratory tests, though this has not been rigorously studied

How status is measured

not routinely measured. There is no laboratory marker for valerian status because it is not an essential nutrient and has no requirement or deficiency state.

In the United States, valerian is sold as a dietary supplement, and dietary supplements are regulated as foods, not drugs. Premarket evaluation and approval by the Food and Drug Administration are not required unless claims are made for specific disease prevention or treatment. Because dietary supplements are not always tested for manufacturing consistency, composition may vary considerably between manufacturing lots.

What the evidence supports

We grade the strength of evidence behind each common reason people take valerian, mirroring how the NIH describes it.